Sony CMD-Z5 - Manual (Page 16)

16 GB
Connecting to the Network
After successfully entering your PIN code, your phone searches for an
available GSM network. The network search is automatic, but may take a
few seconds (see also “Menu Operations-Settings-Preferences” page 60).
You are ready to make and receive calls when the
Network Operator's name appears on the display.
The following indicates the strength of the received network signal. If the
signal is very weak, there is a risk of losing service.
Strong signal Weak signal No service
If you cannot obtain service
One reason for failure to obtain network service is that the reception
strength may be too weak. Try moving to a higher elevation, to a window
or open space. Make sure that there is nothing obstructing the antenna.
Roaming
If you are out of range of your “Home” Network Operator, especially
when you are abroad, another Network Operator may be selected
automatically, subject to signal strength and roaming agreements between
Network Operators. Contact your Network Operator/Service Provider for
details.